Self-relieving ball valve seat

ABSTRACT

A system, in certain embodiments, includes an annular ball valve seat including an annular spring, which biases the annular ball valve seat axially. More specifically, in certain embodiments, the annular ball valve seat includes a main body section, a lip section extending from the main body section, and a seat groove between the main body section and the lip section, wherein the first annular spring is disposed within the seat groove. A first leg of the annular spring biases the lip section in a first axial direction and a second leg of the annular spring biases the main body section in a second axial direction opposite the first axial direction. The annular ball valve seat is configured to be disposed within a ball valve, on either side of a ball of the ball valve. The particular design of the annular ball valve seat enables pressure within a body cavity of the ball valve to be self-relieving.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. patent application Ser. No.12/632,340, entitled “Self-Relieving Ball Valve Seat”, filed on Dec. 7,2009, which is herein incorporated by reference in its entirety.

BACKGROUND

This section is intended to introduce the reader to various aspects ofart that may be related to various aspects of the present invention,which are described and/or claimed below. This discussion is believed tobe helpful in providing the reader with background information tofacilitate a better understanding of the various aspects of the presentinvention. Accordingly, it should be understood that these statementsare to be read in this light, and not as admissions of prior art.

Ball valves may be employed to open or close to enable or block a flowof fluid in a variety of applications. Ball valves typically include abody, an adapter, a rotatable ball disposed within the body and adapter,and a stem coupled to the ball. However, when the ball rotates withinthe ball valve to block the flow of fluid, the fluid under pressure mayoften become trapped in a body cavity of the ball valve. The trappedfluid may increase the pressure under temperature variations, increasingthe torque required to actuate the ball or, if not vented, the pressuremay adversely affect surrounding parts, resulting in leakage or releaseof the fluid to the atmosphere.

SUMMARY OF THE INVENTION

The disclosed embodiments include “floating” ball valve seats, which maybe configured to move (or float) between a ball and body of the ballvalve or between a ball and adapter of the ball valve. This slightmovement, generated by different pressures between a body cavity and abody bore of the ball valve may enable the ball valve seats to releasepressure trapped within the body cavity of the ball valve. Inparticular, in certain embodiments, the ball valve seats may be annularseats, each having a main body section, a lip section extending from themain body section, and a seat groove between the main body section andthe lip section. Annular springs, such as v-shaped or u-shaped metalliccantilever springs, may be inserted into the seat grooves, such that theannular springs bias the main body sections and the lip sections of theball valve seats in opposite axial directions, the seal with the ballhaving a smaller diameter than the seal with the body (or adapter). Dueat least in part to the different sealing diameters, the pressure maydevelop a force that pushes the ball valve seat against the body whenthe cavity pressure is higher than the line pressure. As such, thecavity pressure is allowed to be released close to the line pressure onthe upstream side of the valve, enabling a self-relieving effect of theball valve seat. In addition, the annular springs may be more capable ofretaining their elasticity over time than the elastic main body sectionsof the ball valve seats. Therefore, utilizing the tendency of theannular springs to bias the main body sections and lip sections of theball valve seats in axial directions may improve the overall life cycleof the ball valve seats.

BRIEF DESCRIPTION OF THE DRAWINGS

Various features, aspects, and advantages of the present invention willbecome better understood when the following detailed description is readwith reference to the accompanying figures in which like charactersrepresent like parts throughout the figures, wherein:

FIG. 1 is a cross sectional view of an exemplary ball valve inaccordance with an embodiment of the present invention;

FIG. 2A is a cross sectional view of an exemplary ball valve seat andspring assembled together;

FIG. 2B is a cross sectional view of the exemplary ball valve seat ofFIG. 2A;

FIG. 2C is a cross sectional view of the exemplary spring of FIG. 2A;

FIG. 2D is a perspective view of the exemplary ball valve seat andspring of FIGS. 2A through 2C before installation in the ball valve ofFIG. 1;

FIG. 3 is a cross sectional view of the exemplary ball valve seat andspring of FIGS. 2A through 2D installed in the ball valve of FIG. 1;

FIG. 4 is a cross sectional view of the ball valve of FIG. 1, after theball valve has been closed and pressure has been applied;

FIG. 5 is a cross sectional view of an exemplary ball valve seat on abody side (e.g., upstream side) of a ball of the ball valve, after theball valve has been closed and pressure has been applied, as takenwithin arcuate line 5-5 of FIG. 4; and

FIG. 6 is a cross sectional view of an exemplary ball valve seat on anadapter side (e.g., downstream side) of a ball of the ball valve, afterthe ball valve has been closed and pressure has been applied, as takenwithin arcuate line 6-6 of FIG. 4;

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

One or more specific embodiments of the present invention will bedescribed below. These described embodiments are only exemplary of thepresent invention. Additionally, in an effort to provide a concisedescription of these exemplary embodiments, all features of an actualimplementation may not be described in the specification. It should beappreciated that in the development of any such actual implementation,as in any engineering or design project, numerousimplementation-specific decisions must be made to achieve thedevelopers' specific goals, such as compliance with system-related andbusiness-related constraints, which may vary from one implementation toanother. Moreover, it should be appreciated that such a developmenteffort might be complex and time consuming, but would nevertheless be aroutine undertaking of design, fabrication, and manufacture for those ofordinary skill having the benefit of this disclosure.

Turning now to the figures, an exemplary ball valve 10 is illustrated inFIG. 1. In the presently illustrated embodiment, the ball valve 10includes an annular body 12 and an annular adapter 14. The body 12 andthe adapter 14 of the ball valve 10 are configured to mate with eachother. As illustrated, a ball 16 may fit between the body 12 and theadapter 14 of the ball valve 10. The ball 16 may be configured to rotateabout an axis 18 through an opening 20 in the body 12, as illustrated byarrow 22. Rotation of the ball 16 may enable or block the flow of afluid through the body 12 and the adapter 14 of the ball valve 10. Asillustrated, a pair of seats 24 is disposed on opposite sides of theball 16 to provide seals between the ball 16 and bores (e.g., likecircular passages) within the body 12 and the adapter 14.

In general, a fluid may enter through either the body 12 or the adapter14 and exit through the other. For example, in the illustratedembodiment, fluid may enter through the body 12, as illustrated by arrow26, and may exit through the adapter 14, as illustrated by arrow 28.However, in other embodiments, fluid may enter through the adapter 14and exit through the body 12. In either case, as described in greaterdetail below, the ball 16 between the seat 24 installed in the body 12and the seat 24 installed in the adapter 14 may control the open andclosed positions of the ball valve 10, enabling or blocking the flow ofthe fluid through the ball valve 10. More specifically, in certainembodiments, a valve stem 30 may be inserted within the opening 20through the top of the body 12 and may control rotation of the ball 16between the body 12 and the adapter 14, thereby moving the ball valve 10between a closed position and an open position.

Conventional ball valves require seats to be installed between the bodyor the adapter and the ball, with the seats being designed such thatwhen the ball valve is assembled, both seats are compressed and the seatbodies are substantially deformed. More specifically, a radial-axialelastic-plastic deformation of the seats is used to create a sealbetween the ball and the body and/or the adapter. As described ingreater detail below, the disclosed embodiments may provide for a bodyseat 24 to be installed between the body 12 and the ball 16 and anadapter seat 24 to be installed between the ball 16 and the adapter 14,such that minimal radial-axial compression between the ball 16 and theseats 24 is required. In particular, instead of requiring that the seats24 be pre-loaded by radial-axial compression between the ball 16 and therespective body 12 or seat 14, the particular design of the seats 24 mayonly use axial compression of respective lip sections of the seats 24 toensure adequate sealing between the ball 16 and bores within the body 12and the adapter 14.

In general, in certain embodiments, the body seat 24 and the adapterseat 24 may be similarly designed and may be used interchangeably. FIGS.2A and 2B are cross sectional views of an exemplary seat 24, with itscomponents in an un-deformed condition (e.g., a condition of the seat 24prior to assembly in the ball valve 10). The main body section 32 of theseat 24 has a tapered or shaped surface 34 that comes into contact witha ball surface. On the other side of the main body section 32 of theseat 24 is a groove 36. The annular-shaped seat 24 may be associatedwith an annular-shaped spring 38 which, when assembled, may fit withinthe annular groove 36 of the seat 24. More specifically, FIG. 2C is across sectional view of an exemplary spring 38, which in certainembodiments may be a v-shaped or u-shaped cantilever spring (e.g., aspring cantilevered at a first end and configured to support or resist aforce at a second end) configured to bias in an axial direction relativeto the spring 38 along a central axis 40 of the ball valve 10. However,any type of spring 38 capable of resisting compression in an axialdirection may be used with the body seat 24. In particular, legs 42 ofthe illustrated cantilever spring 38 may resist compression in an axialdirection. After the spring 38 is installed into the groove 36 of thebody seat 24, the spring 38 is held in place by the legs 42, which comeinto contact with first and second protrusions 44 and 46 of the seat 24in such a way that the spring 38 is not able to come out of the groove36. As described in greater detail below, the nature of the spring 38 toresist axial compression may enable the seat 24 to provide a sealbetween a lip section 48 of the seat 24, which comes into contact withthe body 12 or the adapter 14, and the surface 34, which comes intocontact with the ball 16 of FIG. 1. FIG. 2D is a perspective view of thespring 38 and the seat 24 before installation in the ball valve 10.

FIG. 3 is a cross sectional view of the seat 24 after being installed inthe ball valve 10, illustrating the position between the body 12 or theadapter 14 and the ball 16. In the illustrated embodiment, the body seat24 is installed between the body 12 and the ball 16. When installed inthe ball valve 10, the body seat 24 fits into an annular groove createdby the surfaces 50, 52, 54 of the body 12, and the surface 34 of thebody seat 24 contacts the ball 16 on surface 56. Similarly, the adapterseat 24 installed into the adapter 14 fits into an annular groovecreated by the surfaces 58, 60, and 62 of the adapter 14, and thesurface 34 of the adapter seat 24 contacts the ball 16 on surface 56.When the adapter 14 is assembled with the body 12, the lip sections 48of the body seat 24 and the adapter seat 24 come into contact with bodysurface 52 and adapter surface 60, respectively. The lip section 48causes deformation of the lip leg 64 and compression on the legs 42 ofthe spring 38. The spring compression during valve assembly keeps theseats 24 in contact with the body 12, adapter 14, and ball 16, andenergizes the seals when the pressure is applied.

FIG. 4 is a cross sectional view of the ball valve 10 of FIG. 1 havingpressure applied on the body 12 side of the ball valve 10. The body 12and the adapter 14 may be coupled together using various methods. Theball 16 may fit between the body 12 and the adapter 14, wherein the ball16 may enable or block the flow of a fluid through a body bore 66 (e.g.,cylindrical passage) within the body 12 and an adapter bore 68 (e.g.,cylindrical passage) within the adapter 14. In the illustratedembodiment, the fluid enters through the body bore 66 and exits throughthe adapter bore 68. In other words, in the illustrated embodiment, thebody bore 66 is the upstream bore and the adapter bore 68 is thedownstream bore. However, in other embodiments, the flow may be reversedsuch that the fluid enters through the adapter bore 68 and exits throughthe body bore 66. In these embodiments, the adapter bore 68 would be theupstream bore and the body bore 66 would be the downstream bore.

As described above, the ball valve 10 may include a valve stem 30extending radially through the top of the body 12 along the radial axis18 (e.g., perpendicular to the central axis 40). The valve stem 30 maybe rotated about the radial axis 18 by a valve actuator 70, asillustrated by arrow 22. Rotation of the valve stem 30 about the radialaxis 18 may cause the ball 16 to also rotate about the radial axis 18.As the ball 16 rotates about the radial axis 18, the ball 16 may movebetween an open position and a closed position. When the ball 16 is inthe open position, the fluid may be allowed to flow from the body bore66 to the adapter bore 68, or vice versa, relatively unimpeded.Conversely, when the ball 16 is in the closed position, the fluid may beblocked from flowing from the body bore 66 to the adapter bore 68, orvice versa. In both the open or closed positions, the seats 24 mayprovide a seal, generally blocking the flow of fluid into or out of abody cavity 72 between the ball 16 and the body 12 and adapter 14.

In operation, the seats 24 energize and re-energize the seal betweenboth the ball 16 and the body bore 66 and the ball 16 and the adapterbore 68 every time the ball valve 10 is operated, de-pressurized, andthe pressure is applied again. The method for energizing the seal andensuring that the seats 24 stay in contact with the ball 16 during valveoperations and pressure fluctuations is to push against the main bodysections 32 of the seats 24 during assembly of the ball valve 10 bycompressing the ball 16 against the main body sections 32 of the seats24, thereby deforming the lip legs 64 of the seats 24 and compressingthe springs 38. Using this method, the amount of deformation of the mainbody sections 32 of the seats 24 depends on the testing pressure, thesize of the ball valve 10 (e.g., the size of the ball 16, the body 12,the adapter 14, the seats 24, and so forth), the material properties ofthe seats 24, and so forth. However, this deformation is notsignificant, with the deformation taking place in the lip section 48,the lip leg 64, and the annular spring 38 in an axial direction everytime the ball valve 10 is operated and/or the ball valve 10 experiencespressure fluctuations. The lip leg 64 will deform such that the seatsurface 74 contacts the body surface 52 (or the adapter surface 60) whenthe ball load is applied to the seat 24.

In certain embodiments, the seats 24 may be made from plastic materials,or a combination of plastic and metallic materials, with the lip section48 and lip leg 64 made from a plastic material. As a result of thedeformation of the lip section 48 of the seat 24, the lip leg 64 of theseat 24, and the spring 38 during assembly, a contact stress may becreated between the ball 16 and the surface 34 of the seat 24. Thecontact stress between the ball 16 and the seat 24 may affect theoperational effectiveness of the ball valve 10 by, for example,controlling the amount of pressure trapped in the body cavity 72 whenthe ball valve 10 is closed and the fluid within the body bore 66 andthe adapter bore 68 is de-pressurized. Moreover, the amount of pressuretrapped in the body cavity 72 generally depends on the initial pre-loadbetween the ball 16 and the seats 24 during assembly of the ball valve10. The pressure of the fluid trapped in the body cavity 72 generallycauses the torque required to actuate the ball 16 to be higher on thelow-pressure side, thereby reducing the effectiveness of the ball valve10. Therefore, it is beneficial to have the pressure of the fluidtrapped in the body cavity 72 to be as low as possible. The embodimentsdisclosed herein enable the pressure of the fluid trapped in the bodycavity 72 to be self-relieving, as described in greater detail below,thereby reducing the negative effects on the torque of the ball valve10.

More specifically, the disclosed embodiments enable the ball valve 10 tobe assembled with minimal compression between the ball 16 and the seats24. In particular, the seats 24 described herein may function as“floating seats.” In other words, the seats 24 may be configured suchthat the ball 16 may move (or float) axially in either an upstreamdirection (e.g., toward the body bore 66) or a downstream direction(e.g., toward the adapter bore 68). As such, the pressure trapped in thebody cavity 72 may be automatically adjusted based on the upstream anddownstream pressures of the fluid in the body bore 66 and the adapterbore 68, respectively. For example, if the ball 16 moves axially towardthe adapter bore 68, the pressure trapped in the body cavity 72 may bereleased toward the body bore 66 between surfaces of the body seat 24and the ball 16. Conversely, if the ball 16 moves axially toward thebody bore 66, the pressure trapped in the body cavity 72 may be releasedtoward the adapter bore 68 between surfaces of the adapter seat 24 andthe ball 16.

However, despite allowing a certain degree of axial freedom to the ball16, the seats 24 may nevertheless still provide adequate sealing betweenthe ball 16 and the body bore 66 and the ball 16 and the adapter bore68. This is at least partially due to the fact that the main bodysections 32 of the seats 24 are allowed to move slightly, while stillmaintaining a seal between abutting surfaces of the body 12 or theadapter 14. In particular, as described above, springs 38 may exertaxial forces within the main body sections 32 of the seats 24, whichcause lip sections 48 of the seats 24 to push against abutting surfacesof the body 12 or adapter 14.

FIGS. 5 and 6 are intended to illustrate features of an exemplary seat24 and spring 38. For example, FIG. 5 is a cross sectional view of theseat 24 on the body 12 side of the ball 16 of the ball valve 10, astaken within arcuate line 5-5 of FIG. 4, wherein the ball valve 10 hasbeen closed and pressurized. FIG. 6 is a cross sectional view of theseat 24 on the adapter 14 side of the ball 16 of the ball valve 10, astaken within arcuate line 6-6 of FIG. 4, wherein the ball valve 10 hasbeen closed and pressurized.

As illustrated in FIGS. 5 and 6, main body sections 32 of the seats 24may generally be shaped as rectangular sections with carved out sections(e.g., facing the ball 16) extending from approximate midpoints ofradially inward surfaces 76 of the seats 24 to approximate midpoints offirst axial surfaces 78 of the seats 24 (e.g., an axially downstreamsurface 78 of the body seat 24 of FIG. 5 and an axial upstream surface78 of the adapter seat 24 of FIG. 6). Although illustrated as extendingfrom approximate midpoints of the radially inward surfaces 76 and thefirst axial surfaces 78 of the seats 24, in certain embodiments, thecarved out sections of the seats 24 may extend from any point along theradially inward surfaces 76 and the first axial surfaces 78.

Angled surfaces 80 extending from the radially inward surfaces 76 of theseats 24 to the first axial surfaces 78 may be referred to asball-interfacing surfaces 80. As illustrated in FIGS. 5 and 6, incertain embodiments, the ball-interfacing surfaces 80 may actuallyinclude first and second surfaces 34, 82 connected by a tapered section84. As such, only part of the ball-interfacing surfaces 80 may actuallymake contact with the ball 16. More specifically, only the firstball-interfacing surface 34 may make contact with the ball 16. Incertain embodiments, the first ball-interfacing surface 34 may be atapered surface, a curved surface (e.g., a concave surface), or asurface otherwise tailored to the geometry of the ball 16. The firstball-interfacing surfaces 34 have smaller dimensions as compared withthe lip sections 48. Reducing the contact surfaces between theball-interfacing surfaces 80 and the ball 16 may increase the contactpressure between the seats 24 and the ball 16, thereby creating a moreeffective seal.

In addition, the seats 24 may include substantially smaller carved outsections 86 (e.g., beveled edges) extending from the radially inwardsurfaces 76 to second axial surfaces 74 of the seats 24, respectively.These carved out sections 86 may define the size of the surface 74 thatcomes into contact with body surface 52 or adapter surface 60 to ensurefull ball support when the seat 24 is an upstream seat, and to makesurface 74 as a second sealing surface (the first sealing surface beingthe lip section 48) when the seat 24 is a downstream seat.

In addition, as described above, the seats 24 may include grooves 36,within which the springs 38 may be inserted prior to or during assemblyof the ball valve 10. As illustrated in FIG. 2A, each spring 38 may beheld in place within its respective groove 36 by a first protrusion 44extending from the lip section 48 of the seat 24 toward the radiallyoutward surface 88 of the seat 24 and by a second protrusion 46extending from the radially outward surface 88 of the seat 24 toward thelip section 48 of the seat 24.

As illustrated by FIG. 5, the body seat 24 may be held in place within acarved out rectangular groove of the body 12. More specifically, asillustrated, the body seat 24 may be held in place within a radiallyinward surface 50, an axially upstream surface 52, and a radiallyoutward surface 54 of the body 12. In general, the radially inwardsurface 50 of the body 12 and the radially outward surface 54 of thebody 12 are open-ended with ends that are proximate to the ball 16 whenthe ball valve 10 is assembled. During assembly of the ball valve 10,the body seat 24 may be inserted into the carved out rectangular groovedefined by the radially inward surface 50, axially upstream surface 52,and radially outward surface 54 of the body 12. As such, the body seat24 may generally be held in place within the carved out rectangulargroove of the body 12 by the radially inward surface 76 and the radiallyoutward surface 88 of the body seat 24, which abut the radially inwardsurface 50 and the radially outward surface 54 of the body 12,respectively.

Similarly, as illustrated by FIG. 6, the adapter seat 24 may be held inplace within a carved out rectangular groove of the adapter 14. Morespecifically, as illustrated, the adapter seat 24 may be held in placewithin a radially inward surface 58, an axially downstream surface 60,and a radially outward surface 62 of the adapter 14. In general, theradially inward surface 58 of the adapter 14 and the radially outwardsurface 62 of the adapter 14 are open-ended with ends that are proximateto the ball 16 when the ball valve 10 is assembled. During assembly ofthe ball valve 10, the adapter seat 24 may be inserted into the carvedout rectangular groove defined by the radially inward surface 58,axially downstream surface 60, and radially outward surface 62 of theadapter 14. As such, the adapter seat 24 may generally be held in placewithin the carved out rectangular groove of the adapter 14 by theradially inward surface 76 and the radially outward surface 88 of theadapter seat 24, which abut the radially inward surface 58 and theradially outward surface 62 of the adapter 14, respectively.

The springs 38 may energize the seal between the ball 16 and the body 12and the ball 16 and the adapter 14 during operation of the ball valve10. More specifically, as described above, the springs 38 may bev-shaped or u-shaped cantilever springs configured to bias in an axialdirection along the central axis 40 of the ball valve 10. Uponinstallation, the legs 42 of the springs 38 push against the main bodysections 32 of the seats 24 and the lip legs 64 of the seats 24, biasingthe lip sections 48 and lip legs 64 away from the main body sections 32of the seats 24. This tends to bias the lip section 48 and the lip leg64 of the body seat 24 toward the axially upstream surface 52 of thebody 12 and the surface 34 of the body seat 24 toward the surface 56 ofthe ball 16. Similarly, this tends to bias the lip section 48 and thelip leg 64 of the adapter seat 24 toward the axially downstream surface60 of the adapter 14 and the surface 34 of the adapter seat 24 towardthe surface 56 of the ball 16.

Returning now to FIG. 4, when the fluid flows through the ball valve 10and is pressurized at a line pressure P_(line) with the ball 16 in anopen position, and the ball 16 is subsequently rotated into a closedposition, the pressure in the body cavity 72 (P_(cavity)) may beapproximately the same as the line pressure P_(line). If the downstreampressure P_(downtream) in the adapter bore 68 is released, then the ball16 will push against the adapter seat 24 since the line pressure in thebody bore 66 will be greater than the downstream pressure P_(downtream)in the adapter bore 68. As illustrated in FIG. 6, the adapter seat 24supports the ball 16 by the first ball-interfacing surface 34. Inaddition, as illustrated, the lip section 48 and the lip leg 64 of theadapter seat 24 may deform such that the second axial surface 74 of theadapter seat 24 contacts the axially downstream surface 60 of theadapter 14. As such, when this happens, the adapter seat 24 may supportthe entire load of the ball 16. At the same time, as illustrated in FIG.5, the spring 38 within the body seat 24 may relax such that the axialsurface 74 of the body seat 24 moves away from the axially upstreamsurface 52 of the body 12 and only the lip section 48 of the body seat24 remains in contact with the axially upstream surface 52 of the body12. The body seat 24 moves with the ball 16 such that the seat surface34 remains in contact with the surface 56 of the ball 16.

If the line pressure P_(line) on the upstream side of the ball 16decreases, the body cavity pressure P_(cavity) may be greater than theline pressure P_(line) in the body bore 66. As a result, since theaxially upstream surface 52 of the body 12 contacts with the lip section48, which has a greater diameter than the surface 34 which contacts theball 16, a force F_(n) will be created from the body cavity 72 whichpushes the body seat 24 away from the ball 16 axially (e.g., the secondaxial surface 74 and the lip section 48 of the body seat 24 approach theaxially upstream surface 52 of the body 12), temporarily moving the ballsurface 56 away from the seat surface 34, allowing the body cavitypressure P_(cavity) to decrease to a pressure close to the line pressureP_(line) in the body bore 66. This illustrates the self-relieving effectof the seats 24 described herein.

Conversely, if the line pressure P_(line) on the upstream side of theball 16 increases, the line pressure P_(line) will cause the lip section48 of the body seat 24 to move away from the axially upstream surface 52of the body 12, allowing the body cavity pressure P_(cavity) to increaseto a pressure close to the line pressure P_(line) in the body bore 66.Therefore, both increases and decreases in the line pressure P_(line)will lead to the body cavity pressure P_(cavity) remaining relativelyclose to the line pressure P_(line) in the body bore 66.

As a further example, in the event that the fluid trapped within thebody cavity 72 increases in volume (e.g., due to temperaturevariations), the resulting body cavity pressure P_(cavity) may increaseand the self-relieving effect of the body seat 24 may again cause thebody seat 24 to push away from the ball 16, allowing the body cavitypressure P_(cavity) to decrease to a pressure close to the line pressureP_(line) in the body bore 66. More specifically, the fluid may releasefrom the body cavity 72 into the body bore 66 between the ball 16 andthe body seat 24.

An advantage of the disclosed embodiments is that the main body sections32 of the seats 24 are not substantially deformed during assembly of theball valve 10. More specifically, the only substantial deformation ofthe seats 24 during assembly of the ball valve 10 are to the lipsections 48 and lip legs 64, which are biased by the springs 38 in anaxial direction, and the springs 38. As such, there is minimaldeformation of the main body sections 32 of the seats 24 during assemblyof the ball valve 10. In addition, the seats 24 primarily utilize theelastic properties of the springs 38 to energize the seals of the ballvalve 10, instead of relying on the plastic material properties of themain body sections 32 of the seats 24. In general, the springs 38 may bemore capable of retaining their elasticity over time than deformedplastics. As such, the seats 24 may experience longer life cycles thanother seats, which are substantially pre-loaded through deformation asdescribed above. Moreover, the deformation of the lip section 48 onlyinsignificantly impacts the torque required to actuate the ball 16,thereby enhancing the effectiveness of the ball valve 10. Furthermore,since the compressive mechanical characteristics of the main bodysections 32 of the seats 24 are less important in the disclosedembodiments, the materials used for the main body sections 32 of theseats 24 may be chosen from a larger variety of materials, enabling theseats 24 disclosed herein to be used in both low-pressure andhigh-pressure ball valves 10.

While the invention may be susceptible to various modifications andalternative forms, specific embodiments have been shown by way ofexample in the drawings and have been described in detail herein.However, it should be understood that the invention is not intended tobe limited to the particular forms disclosed. Rather, the invention isto cover all modifications, equivalents, and alternatives falling withinthe spirit and scope of the invention as defined by the followingappended claims.

The invention claimed is:
 1. A seat system, comprising: a first unitaryannular seat configured to be disposed within a first groove of a bodyof a ball valve and to contact a ball of the ball valve, wherein thefirst unitary annular seat comprises: axially opposite first and secondsurfaces, the first surface comprises a first straight angled portionand a second straight angled portion, the first straight angled portiondefines a first length and the second straight angled portion defines asecond length, the second length is greater than the first length, thefirst and second straight angled portions are radially offset from eachother and acutely angled relative to a central axis of the first unitaryannular seat, the radial offset is configured to block contact betweenthe first straight angled portion and the ball such that the firststraight angled portion does not contact the ball while the ball valveis in a closed position with the first unitary annular seat downstreamsuch that a first pressure in a first passage on a first side of theball adjacent to the first unitary annular seat is less than a secondpressure in a second passage on a second side of the ball opposite fromthe first unitary annular seat, and the first unitary annular seat isconfigured to self-relieve.
 2. The seat system of claim 1, wherein thesecond surface of the first unitary annular seat is configured tocontact the body to form a first seal at a first diameter, the secondstraight angled portion of the first surface of the first unitaryannular seat is configured to contact the ball to form a second seal ata second diameter.
 3. The seat system of claim 1, wherein the firstunitary annular seat comprises a first main body section, a first lipsection extending from the first main body section, and a first seatgroove between the first main body section and the first lip section,wherein an annular spring is disposed within the first seat groove, andthe annular spring is configured to bias the first and second surfacesof the first unitary annular seat axially away from one another alongthe central axis.
 4. The seat system of claim 3, wherein the annularspring comprises a first leg that biases the first lip section in afirst axial direction along the central axis and a second leg of theannular spring biases the first main body section in a second axialdirection along the central axis opposite to the first axial direction.5. The seat system of claim 4, wherein the annular spring biases thefirst lip section against a first surface of the first groove, and theannular spring biases the first main body section away from the firstsurface of the first groove and against the ball.
 6. The seat system ofclaim 1, wherein the first and second straight angled portions areradially separated by a connecting portion, and the connecting portionis perpendicular to the central axis.
 7. The seat system of claim 1,comprising a second unitary annular seat configured to be disposedwithin a second groove of an adapter of the ball valve and to contactthe ball, wherein the second unitary annular seat comprises axiallyopposite third and fourth surfaces, and the second unitary annular seatis configured to self-relieve.
 8. The seat system of claim 7, whereinthe second unitary annular seat comprises a second main body section, asecond lip section extending from the second main body section, and asecond seat groove between the second main body section and the secondlip section, wherein a second annular spring is disposed within thesecond seat groove, the second annular spring is configured to bias thethird and fourth surfaces of the second unitary annular seat axiallyaway from one another along the central axis.
 9. The seat system ofclaim 8, wherein the second annular spring comprises a second leg thatbiases the second lip section in a third axial direction along thecentral axis and a fourth leg of the second annular spring biases thesecond main body section in a fourth axial direction along the centralaxis opposite to the third axial direction.
 10. The seat system of claim1, comprising the body.
 11. The seat system of claim 7, comprising theadapter.
 12. A system, comprising: a unitary annular ball valve seatdisposed within an annular groove of a valve housing for use in a ballvalve, wherein the unitary annular ball valve seat comprises a main bodysection and a lip section, the main body section defines opposite firstand second axial surfaces and radially-inner and radially-outercircumferential surfaces, and the lip section is recessed below theradially-outer circumferential surface; and an annular spring disposedwithin a seat groove of the unitary annular ball valve seat, wherein theseat groove extends radially into the radially-outer circumferentialsurface of the unitary annular ball valve seat at a position axiallybetween the first and second axial surfaces of the unitary annular ballvalve seat, the annular spring biases the opposite first and secondaxial surfaces of the unitary annular ball valve seat axially intocontact with a ball and the valve housing, and the annular springcomprises a first leg and a second leg that are configured to beparallel to one another such that respective radially-outer ends of thefirst leg and the second leg are separated by a first axial distanceduring certain pressure conditions within the ball valve and to beangled relative to one another such that the respective radially-outerends of the first leg and the second leg are separated by a second axialdistance that is less than the first axial distance during otherpressure conditions within the ball valve.
 13. The system of claim 12,wherein the first leg of the annular spring biases the lip section in afirst axial direction, and the second leg of the annular spring biasesthe main body section in a second axial direction opposite the firstaxial direction.
 14. The system of claim 12, wherein the unitary annularball valve seat comprises an angled surface configured to interface withthe ball, the angled surface comprises a first surface configured tomake contact with the ball, a second surface configured not to makecontact with the ball, and a tapered section connecting the first andsecond surfaces.
 15. The system of claim 12, wherein the annular springis a u-shaped spring.
 16. The system of claim 12, wherein the annularspring comprises a metallic cantilever spring.
 17. A system, comprising:a valve housing comprising an annular groove; a ball disposed in thevalve housing; a unitary annular ball valve seat disposed within theannular groove, the unitary annular ball valve seat comprising axiallyopposite first and second axial surfaces, the first surface comprises afirst straight angled portion and a second straight angled portion, thefirst straight angled portion defines a first length and the secondstraight angled portion defines a second length, wherein the secondlength is greater than the first length, wherein the first and secondstraight angled portions are radially offset from each other and acutelyangled relative to a central axis of the unitary annular ball valveseat, wherein the radial offset is configured to block contact betweenthe first straight angled portion and the ball such that only the secondstraight angled portion, and not the first straight angled portion,contacts the ball while the ball is in a closed position within thevalve housing with the unitary annular ball valve seat downstream suchthat a first pressure in a first bore on a first side of the balladjacent to the first unitary annular seat is less than a secondpressure in a second bore on a second side of the ball opposite from thefirst unitary annular seat, and wherein the unitary annular ball valveseat is configured to self-relieve; and an annular spring disposedwithin a seat groove of the unitary annular ball valve seat, wherein theseat groove extends radially into a radially-outer circumferentialsurface of the unitary annular ball valve seat at a position axiallybetween the first and second axial surfaces of the unitary annular ballvalve seat, and the annular spring biases the opposite first and secondaxial surfaces of the unitary annular ball valve seat axially intocontact with the ball and the valve housing.
 18. The system of claim 17,wherein the first and second straight angled portions are radiallyseparated by a connecting portion, and the connecting portion isperpendicular to the central axis.
 19. The system of claim 17, whereinthe annular spring is a u-shaped spring that comprises a first leg and asecond leg that are configured to be parallel to one another such thatrespective radially-outer ends of the first leg and the second leg areseparated by a first axial distance during certain pressure conditionsduring certain pressure conditions across the ball and to be angledrelative to one another such that the respective radially-outer ends ofthe first leg and the second leg are separated by a second axialdistance that is less than the first axial distance during otherpressure conditions across the ball.
 20. The seat system of claim 1,wherein the second surface of the first unitary annular seat comprises amidpoint along a radial axis of the first unitary annular seat, and themidpoint is configured to contact the body while the ball valve is inthe closed position with the first unitary annular seat downstream suchthat the first pressure in the first passage on the first side of theball is less than the second pressure in the second passage on thesecond side of the ball.